Timber has long since been a popular building material, but over the last several hundred years, its use has largely been limited to smaller structures with concrete and steel serving as the foundation for many large modern structures. However, as new forms of mass timber products are developed, wood is once again becoming a popular material choice for large structures. As more and more mass timber projects come online, the knowledge-base surrounding mass timber grows, further widening the field of adoption. One of the projects currently demonstrating the benefits of mass timber construction is the Ellis Preserve Mass Timber Office Building. The mass timber office building is part of Equus Capital Partners’ Ellis Preserve, which began in 2004 when they acquired the 218-acre site of the former Ellis School. With a history stretching back to the 1700s, the last two decades has seen this parcel of land at the heart of Newtown Square transformed into a distinctive integrated campus for office, retail, residential, and community use–incorporating the area’s unique history with spaces designed to provide new opportunities for the surrounding community. The final piece of Ellis Preserve’s 20-year transformation is a 105,000-square-foot mass timber office building, which is currently under construction. Although this mass timber office building represents the final project in the 20-year redevelopment of Ellis Preserve, the impetus for this unique capstone stretches back over a decade to when Equus began working on a new headquarters. Located within the 218-acre Ellis Preserve site was a Vanity Fair manufacturing building which was over a century old. As the process of redeveloping the space was taking place, a portion of the building was slated to be torn down, and it was discovered that the structure contained a significant amount of timber in the form of heavy framing and nail laminated timber (NLT) flooring. Wanting to find ways to reuse these historical timber elements, the team took a trip to the building site. According to John Schwartz, Managing Member at D2 Groups llc., the result of this trip was that “ideas started flowing” about how the beams could be reused within the structural design of the new building. The result was a two-story building at Equus Headquarters that uses the previous structure’s heavy timber as purlins in the framing of the roof structure. In addition, the structure is filled with furniture, walls and floor constructed from reclaimed wood from the Vanity Fair building. Schwartz says that the reaction from tenants and the real estate community to the new structure was resoundingly positive, leading them to begin looking at incorporating timber into the design of other projects and buildings. David Seace, Architecture Studio Director at D2 Groups llc., said that positive reaction to the project at Equus’ headquarters started the conversation about how they could continue incorporating timber elements into more of their projects moving forward, and, around this time, they were in the process of designing a five-story office building–675 Swedesford Road. In the initial design phases of the 675
Swedesford project, the building was envisioned as a steel structure on a conceptual level. Using their experience incorporating mass timber materials into the design of Equus’ headquarters, the team began looking at the five-story office building from the lens of mass timber and ultimately chose to pursue a mass timber design. While the 675 Swedesford project was in the construction phase, the conceptual phase of Ellis Preserve’s final step was just beginning. Dennis Mordan, President at O’Donnell & Naccarato, says that, unlike the 675 Swedesford and Equus headquarters projects, the 105,000-square-foot office building has been envisioned as a mass timber project from its inception. Mordan points out that their extensive experience in executing mass timber projects has shown them that similar projects would be viable moving forward. For mass timber projects like the Ellis Preserve Office Building, Mordan says the design difference between using mass timber and traditional materials is “predominantly in the early construction administration phase,” likening the process to “essentially a prefabricated erector set.” With a mass timber design in place for the new structure at Ellis Preserve, the major challenge was executing these early construction administration steps such as coordinating openings, size, and connections. The construction team worked with the material supplier to produce shop fabrication drawings to ensure the connections were completed. For mass timber projects, this early construction administration phase is typically a little bit longer than traditional alternatives. During this phase, there are a number of details that need to be finalized, and, to accomplish this task for the Ellis Preserve project, Mordan says the team held weekly coordination meetings for around 10 weeks during this phase. With these details finalized, however, the next steps of the project progressed rapidly. Whereas steel and concrete projects are limited by the curing time of slabs, mass timber projects are able to progress rapidly forward once the construction phase is initiated. Steve Spaeder, Principal & Senior Vice President at Equus Capital Partners, believes this final project nearing completion at Ellis Preserve represents a historical significance to the development of buildings and construction. Referencing the site’s history, Spaeder notes the development of the site’s previous structures from the earliest timber structures to later steel and concrete. Spaeder notes the significance of the final structure on the development being mass timber, and that it shows us the way forward. Whereas traditional forms of timber represented the best available choice for our forebears, new forms of mass timber products are emerging as best available choices for projects across the United States. Projects and developments like Ellis Preserve and its mass timber office building and Equus Headquarters are representative of this expanding development, and point to wider adoption as knowledge and expertise around mass timber increases.
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Spring 2024 csengineermag.com
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